The changes to the magical world regarding the casual destruction of magical artifacts are far more significant to changes to irrational!Harry's decision making.
The concept of "artifact" isn't nearly as neatly delineated in Harry Potter canon as in the MoR!Verse.
In canon, it's Horcruxes that are very hard to destroy -- other magical objects not necessarily so. I don't believe there's anything even in canon that would have prevented Harry from snapping the Elder Wand in two.
While never being explicitly discussed either way casual destruction of artifacts as powerful as the deathly hallows doesn't happen in Harry Potter. It occurring in the movies is something new and I am comfortable with my initial reaction of surprise and disappointment. I hope MoR doesn't base its own magical reality on the one evidently depicted in the movies because it just wouldn't be either as appealing or as coherent.
Update: Discussion has moved on to a new thread.
The hiatus is over with today's publication of chapter 73, and the previous thread is approaching the 500-comment threshold, so let's start a new Harry Potter and the Methods of Rationality discussion thread. This is the place to discuss Eliezer Yudkowsky's Harry Potter fanfic and anything related to it.
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: one, two, three, four, five, six, seven. The fanfiction.net author page is the central location for information about updates and links to HPMOR-related goodies, and AdeleneDawner has kept an archive of Author's Notes.
As a reminder, it's often useful to start your comment by indicating which chapter you are commenting on.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: